Also accept buffer in Connection.send and .sendall

Not at all sure what i am doing, but according to
http://hg.python.org/cpython/rev/9e718d8f71e8/, buffers are a accepted
type to pass to sendall in Python 2.6.
Merge pull request #99 from untitaker/python26-buffers

Fix the type checking in Connection.send and Connection.sendall to allow values of the `buffer` type on Python 2.